Improvement in rock-drills



N o 2 O 0 6 9 0.

C. BURLEIGH. Rook-Drill.

UNITE-ESTATES PATENT OFFICE.

CHARLES BURLEIGH, OF FITOHBURG, MASSACUSETTS.

IMPROVEMENT IN ROCK-DRILLS.

Specification forming part of Letters Patent No. 200,690, dated February26, 1878; application led January 29, 1876.

To all whom it may concern:

Be it known that I, GHARLEs BURLEIGH, of Fitchburg, in the county ofWorcester and State of Massachusetts, have invented an Improvement inRock-Drills, of which the following is a specification:

This invention relates to improvements in rock-drills adapted to beoperated by steam or compressed air.

In United States Letters Patent, No. 162,528, heretofore grantedto me,the levers in the steam or air passages are operated by the annularcamsurfaces carried by the piston-head, have their outer ends placed inopenings or compartments in the valve-rod, and the levers move thevalverod and always move with it. It is desirable to move the valve-rodas quickly and with as little expenditure of power as possible, and inthis instance I have dispensed with the outer sides of the so-calledcompartments of the valve-rod, and have made provision whereby the airor steam admitted into a passage whereever a valve-moving lever issituated will act immediately on the head of the valve-rod and move itin advance of the action of the lever, after the lever shall havestarted the valve, so as to permit the free steam to meet that end ofthe lever.

In that patent the stem of the valve-rod extended outside the cylinderthrough a stuftn gbox, and one end of the rod is subjected toatmospheric changes; but in the present invention the valve-rod isentirely within the casing, and the surfaces at its ends against whichthe steam works are equal, and the end of the valve-rod, heretoforeextended into the atmosphere through a stuffing-box, is dispensed-with,reducing the weight of the valverod, its friction, and lessening thepower required to move it; and both ends of the valverod are always ofthe same temperature, and the valve-rod is not liable, by an accidentalblow, to be bent or broken.

The hand-lever adapted to move the valverod to start the machine is, inthe patent, passed through a -hole in the extended valverod; but in thepresent instance a inger on a shaft or -pin enters a slot in the back ofthe valve, such construction enabling me to dispense with the extendedend of the rod and greatly reduce its weight and operate it in a betterand more satisfactory manner.

Figures 1 and 2 represent the casing and piston, or drill-carrier, andvalve-mechanism, the latter being in section, and with the valverod inits two extreme positions. Fig. 3 represents the valve-rod andpacking-segments removed; Fig. 4, an end view of the packingsegments;and Fig. 5, a top view of the shaft or pin that carries the fingeradapted to move the valve-rod.

The bed-plate or frame of the machine and the feeding-screw to advancethe drill and mechanism to rotate the piston-rod, (neither shown in thepresent case,) and the cylinder a, piston b, piston-rod c, valve-movinglevers d, annular portions c on the piston, and the valve f, are allsubstantially as represented in the patent before mentioned. Thevalve-rod g reciprocates in packing segments h, inclosed within acontractile steel or metal ring, i, both placed in openings to receivethem in the case and adapted to keep the segments close against the rod;and each end of the valve-rod is provided with a head, j, against whichthe air or steam acts whenever the rod and valve are moved a little bythe lever; for the steam, rushing into the passage in which the leverjust operated or slightly moved by the annular projection is situated,acts against the head j, and throws the valve-rod and valve quickly intoits opposite position, the entire stroke to move the valve in eitherdirection being a pushing stroke, and subjecting the valve-rod only tocontractile strain.

The valve-rod g is arranged entirely within the casing, and is protectedfrom the action of the atmosphere and the liability of accidents fromblows, and is made as short and light as possible, and the steam, inmoving the valve, presses at each end on heads of like area. The iingerla to engage the valve-rod to start the machine, enters a slot at theback of a block, l, on the valve-rod, the block carrying the valve f,which is removable therefrom. This finger projects from a rocking arm orshaft, m, mounted in close bearings in the case, and provided with athumb-nut, n, or lever by which to turn it and the finger to start themachine should the valve not be in the proper position; and a spring, o,bearing on a square or llat portion of the shaft, turns it, whenreleased, immediately back to its central position, Where it is notmoved by the valverod during its reeiprocations.

The air or steam inlet and exhaust passages are as described in my otherpatent, and the piston-rod and its attached drill are operated in theusual aud well known Way.

I claim- 1. In a rock-drill, a rigidly-connected valve and valve-rod,arranged entirely Within the case, in combination with levers adapted tobe moved by the piston to start the valve-rod, substantially as and forthe purpose described.

CHARLES BURLEIGH.

Witnesses R. L. ROBERTS, L. H. LATIMER.

